BALTIMORE (AP) ' Baltimore police officers deleted videos from a man's mobile phone after he recorded a confrontation between officers and a female friend at the 2010 Preakness Stakes, violating his constitutional rights and wiping away a year and a half of memories of his young son, according to a lawsuit filed Tuesday.

The suit filed by the American Civil Liberties Union of Maryland challenges the detention of Christopher Sharp, the seizure of his phone and the deletion of the recordings as unconstitutional. The ACLU argued that law enforcement officers in Maryland, including Baltimore police officers, "routinely threaten to arrest or punish civilians who document police activity, using the Maryland Wiretap Act and related, inapplicable infractions to back up these threats."

The suit filed in Baltimore Circuit Court named the city's police department, its commissioner and three unnamed officers. Baltimore police spokesman Anthony Guglielmi declined to comment on the pending case. But he said that if a cell phone is seized as evidence, the usual procedure would be to submit it to the evidence control unit and obtain a search warrant to review the video.

Sharp and two friends watched the Preakness Stakes last year from the grandstands and later went into the clubhouse, where Sharp noticed one of those friends being "forcibly arrested" and recorded the incident on his mobile phone, according to the lawsuit.

In a news release on the suit, the ACLU cites video shot by another bystander and posted on YouTube that shows officers struggling with the woman in a yellow skirt and sandals on the floor. Blood drips from her face as officers scream at her to put her hands behind her back.

The woman was charged with assaulting an officer, resisting arrest and other offenses and later pleaded guilty to second-degree assault and received probation before judgment.

Officers and a sergeant told Sharp that he had to turn over his phone as evidence, but he was hesitant, he said Wednesday in an interview with The Associated Press. When he finally handed over the phone ' Sharp said ' instead of just making a copy, the sergeant wiped out the videos and all other data on his phone, down to the alarms Sharp had set for himself and returned the phone.

At the time he was just glad to have the phone back and not be under arrest, but then he realized he had lost a year and a half of memories of his son, including trips to the beach and the fair and basketball and soccer games, he said.

"I think it's a major violation," Sharp said. "It was just normal procedure for them: covering their backs and they didn't care really how it affected anyone else."

He was also disturbed that it wasn't just one officer. He said a group of officers appeared to work together.

Sharp said he was raised to trust law enforcement agents but was shaken by the incident.

"I always had a respect for police. It has certainly affected the way I feel. I don't know that I'll get that back again," he said.

The lawsuit asserts that Sharp's recording was protected by the First Amendment because Maryland allows citizens to record officers during public acts. It accuses the officers of violating Sharp's free-speech rights and his freedom from unreasonable searches and seizures. It also claims false imprisonment and invasion of privacy by the officers.

"Police officers doing their jobs in a public place are accountable to the public they serve, and camera phones have become an important accountability tool," said ACLU Legal Director Deborah Jeon.

She added: "It is antithetical to a democracy for the government to tell its citizens that they do not have the right to record what government officials say or do or how they behave in public."

The suit requests an injunction barring Baltimore police from punishing anyone who makes audio recordings of officers performing duties in public. It also seeks unspecified compensation for Sharp's suffering and property damage.